The 33-year-old Wheldon was pronounced dead at 1:54 p.m. Sunday at University Medical Center in Las Vegas, where he was flown by medical helicopter after the crash at the track about 12 miles away.

After an autopsy, Murphy ruled the death an accident, the result of blunt trauma to the head due to motor vehicle collision, and offered condolences to friends and family of the married father of two from England.

"We'll be working with family and IndyCar officials and the attending physicians to fully review the case in an effort to improve safety for drivers," he told The Associated Press.

Three other drivers were injured in the fiery Lap 11 crash, none seriously.

Pippa Mann, 28, had surgery on a burned right pinkie finger and
was released Monday, as was 23-year-old JR Hildebrand, who had a
bruised sternum. Will Power, 30, was evaluated and released Sunday.

The race was called off after Wheldon's death was announced, although drivers drove a five-lap salute to their colleague.

Las Vegas Motor Speedway president Chris Powell said Monday that it was too early to decide whether IndyCar should return to the 1.5-mile oval but fully supported the decision to stop the race.

Wheldon was airlifted from the Las Vegas track at 1:19 p.m. local time Sunday and taken to the hospital, becoming the first IndyCar driver to die on the track since rookie Paul Dana was killed in practice on the morning of race day at Homestead-Miami Speedway in 2006.

Dana's widow, Tonya Bergeson-Dana, told ESPN's "Outside The Lines" on Monday that she wanted Wheldon's family to know "there are people who know, to a degree, what they're going through and that we're here for them."

Bergeson-Dana added: "A common misperception is that they're in it for that feeling of danger -- that was not the case with Paul, he was in it for the challenge. The challenge was in getting the most out of himself and out of the car. It was not about the danger, it was about the possibilities of what could be accomplished."

Wheldon, who came to the United States from England in 1999, won 16 times in his IndyCar career and was the series champion in 2005, the year he won his first of two Indianapolis 500 titles.

Despite winning this year's Indy 500, Wheldon couldn't put together a full-time ride this season. He landed in this race thanks to IndyCar CEO Randy Bernard's promise of $5 million to any moonlighting driver who could win the IndyCar season finale at Vegas. Although there were no takers, Bernard refused to scrap the idea and Wheldon was declared eligible for the prize.

Drivers had been concerned about the high speeds at the track, where they were hitting nearly 225 mph during practice.

Information from The Associated Press and ESPN Enterprise Unit producer Willie Weinbaum was used in this report.